The present invention relates to a light emission display panel.
As a self emission type light emission display panel, an organic electroluminescence (hereinafter called organic EL) is noticed because of high efficiency, long life and high fineness.
FIGS. 6a and 6b show a conventional organic EL display panel. The organic EL display panel comprises a transparent glass substrate 1, and a first electrode 2 comprising a plurality of transparent strips of anodes 2 formed on the glass substrate 1 into parallel lines. The first electrode 2 is made of ITO by patterning processes (for example a pitch of 0.3 mm, width of 0.28 mm, thickness of 0.2 mm). On the first electrode 2, a light emission layer 7 comprising an organic hole transporting layer 3, light emission organic layer 4, and organic electron transporting layer 5 is coated by the evaporation method. Furthermore, a second electrode 6 comprising a plurality of strips as metallic cathodes is formed on the light emission layer 7 into parallel lines so as to intersect the first electrode 2. The second electrode 6 is formed on the layer 7 by a method such as evaporation, CVD, PVD, or spattering, using a metal mask of FIG. 7. The display panel is sealed for the prevention of humidity.
The intersection of each first electrode 2 and second electrode 6 is a pixel which emits light by applying a voltage to the electrodes.
Referring to FIG. 7, the metal mask for the evaporation has a plurality of openings 8 and partitions 9 between the openings 8. The openings 8 are formed by the number of the second electrodes and has a shape equal to the shape of the second electrode.
The width of the opening 8 is several hundreds microns, and the width W of the partition 9 is several tens microns.
Because of such an extremely small dimension, the metal mask has a small mechanical strength, and hence it is liable to be broken of bent. Furthermore, there is a problem that adjacent electrodes contacts with each other in the production of the display panel. In order to solve such problems, it is thinkable to increase the thickness of the metal mask. However, there is a limit to produce a high fineness film. Hence, the thickness of about 0.1 mm is a limit. On the other hand, if the width W is increased, the interval between pixels increases, which means the retrogression against the tendency to fineness of the pixel.